DE 10 2008 043 735 A1 describes a method for producing a bond connection between at least two wafers. The method described therein comprises application of a first bonding material on a first wafer, aluminum or an aluminum alloy being selected as the first bonding material.
The method furthermore describes the application of a second bonding material on a second wafer, gold being selected as the second bonding material. In the method described therein, a bonding process is subsequently carried out, the first and the second bonding materials being bonded to one another and a wafer-to-wafer bond thereby being produced between the first wafer and the second wafer.
Furthermore, EP 1071126 B1 describes the bonding together of two wafers, various bonding materials being described as suitable for the bonding pads of the two wafers, and bonding pads consisting of gold being used. Furthermore, silicon, indium, aluminum, copper, silver and alloys of these elements are described therein as bonding materials.
FIG. 4 shows an exemplary arrangement 1 of two wafers 10, 20. A first wafer 10 is used as a cap wafer of the arrangement. A second wafer comprises an MEMS region 15 and an ASIC region 5. Metal bonding pads 21, 22, 23 are provided for contacting the second wafer. The MEMS region 15 comprises an MEMS structure with a free-standing tongue structure 18, which comprises a strain gauge 16.